Pressure relief valves have found many uses, one of which is in the construction of inflatable life rafts. Such life rafts are ordinarily inflated by means of a compressed gas cylinder which discharges the gas, usually carbon dioxide, to the interior of the raft. Care must be taken that the raft is not subjected to too high a pressure when inflated at very high temperature. On the other hand, sufficient gas must be inserted, even at very low temperatures, to insure proper inflation. In order to permit the raft to be inflated as quickly as possible a relatively high volume supply of gas must be provided and consequently, once the proper pressure is attained within the raft, the discharge capacity of the relief valve must be sufficient to permit that high volume of gas to be released. In the past, pressure relief valves employed in inflatable life rafts have been somewhat restrictive when it has been attempted to pass a large volume of gas. In order to make these valves sufficiently sturdy, safe and foolproof, the relative dimensions of its parts have left a relatively small orifice through which the gas may escape.